It has already been proposed that certain arylboron compounds are used as antifouling agent. Thus, Japanese Patent Publication No. 1571/79 discloses tetraphenylboron compounds having the general formula: ##STR2## wherein X represents a potassium atom, an ammonium radical or a quaternary organic nitrogen-containing group which may form a nitrogen-containing heterocyclic group and has been exemplified by pyridinium, 4-methylpyridinium and 3-bromopyridinium group. U.S. Pat. No. 3,211,679 proposes triphenylboron compounds having the general formula: ##STR3## wherein Y represents a hydrogen atom, a halogen atom or a lower alkyl group, as antifouling agent.
As is well-known and experienced, the attachment and growth of a variety of aquatic organisms including small animals such as barnacles, serpulae, Hydroides norvegica (Gunnerus), sea squirts, sea mussels, oysters, etc.; algae such as sea lettuces, green lavers, eclocarpus, ulotrichales, etc.; and various bacteria, molds and diatoms generally called "slimes" onto ship's hull, particularly bottom and water line thereof, internal surfaces of intake and cooling pipes in power stations and various structures in sea and fresh water such as fish preserves, fishing nets and others result in a number of serious drawbacks from the maintenance and conservation points of view. Thus, in cases of ships, frictional resistance of the hull to passage through water is substantially increased, resulting in large economical losses such as decrease in fuel efficiency and maximum speed of the vessel and in necessity of periodic costly operations for the removal of such accumulated foulings. In cases of fish preserves and fishing nets, there occur such serious damages as tardy growth of bred fishes and oxygen-deficiency, whereas in case of a fixed shore net, such deficiencies as floating off of the net and resulting poor catch of fishes. For internal surfaces of cooling pipes and the like, there are such faults as clogging of heat exchangers and resulting interruption of the operation and poor cooling efficiency.
Hitherto, various measures have been proposed to prevent the attachment and growth of aquatic organisms on ship's hull and other aquatic structures in sea and fresh water. Most typically, there have been used many kinds of antifouling paints of which active ingredients are cuprous oxide, copper rhodanide, organotin compounds, organotin polymers, thiocarbamates and others. Certain tetraphenylboron compounds have also been proposed in Japanese Patent Publication No. 1571/79 above-referred to as low-toxicity antifouling agents, but they are still not perfectly satisfactory in their durability of the antifouling activities.
We have made many investigations, with the intention of obtaining new organoboron compounds having an effective antifouling activity over a prolonged period of time with retention of such low toxicity as shown in the known tetraphenylboron compounds above-mentioned, on the preparation of a number of organoboron compounds and on tests for evaluating the utilities of these compounds as antifouling agent. As a result, we have found that a series of new tetraarylboron-ammonium complexes as hereinafter defined exhibit unexpectedly long-lasting antifouling activities with satisfactorily low toxicity, thus making them appraisable to be such superior as antifouling agent to the known tetraphenylboron compounds.
We have extended our studies on these new complex compounds to their other properties and found that they also possess high anti-microbial activities against, for example, fungi such as genera Aspergillus, Penicillium, Rhizopus and Fusarium; bacteria such as genera Bacillus and Pseudomonas; and yeasts and are thus useful as antibacterial and antifungal agents for non-medicinal uses, particularly as antiseptic and antifungal agents for industrial uses.